Return-Path: <linux-kernel-owner+w=401wt.eu-S1754861AbYC1PyR@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754861AbYC1PyR (ORCPT <rfc822;w@1wt.eu>);
	Fri, 28 Mar 2008 11:54:17 -0400
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753680AbYC1Px7
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Fri, 28 Mar 2008 11:53:59 -0400
Received: from mtagate7.de.ibm.com ([195.212.29.156]:50349 "EHLO
	mtagate7.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1753121AbYC1Px6 (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Fri, 28 Mar 2008 11:53:58 -0400
Subject: Re: [patch 09/10] Hugetlb common code update for System z.
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Reply-To: schwidefsky@de.ibm.com
To: Ingo Molnar <mingo@elte.hu>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>,
       Andrew Morton <akpm@linux-foundation.org>, haveblue@us.ibm.com,
       linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
       "David S. Miller" <davem@davemloft.net>,
       Tony Luck <tony.luck@intel.com>, Paul Mackerras <paulus@samba.org>,
       Thomas Gleixner <tglx@linutronix.de>, Paul Mundt <lethal@linux-sh.org>
In-Reply-To: <20080328140634.GA29218@elte.hu>
References: <20080312173155.703966894@de.ibm.com>
	 <20080312173218.186436562@de.ibm.com>
	 <1205344286.9828.91.camel@nimitz.home.sr71.net>
	 <1205363937.5237.60.camel@localhost.localdomain>
	 <20080312164303.cac9cab5.akpm@linux-foundation.org>
	 <1206713119.5186.52.camel@localhost.localdomain>
	 <20080328140634.GA29218@elte.hu>
Content-Type: text/plain
Organization: IBM Corporation
Date: Fri, 28 Mar 2008 16:53:19 +0100
Message-Id: <1206719599.6592.10.camel@localhost>
Mime-Version: 1.0
X-Mailer: Evolution 2.12.3 
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1762
Lines: 39

On Fri, 2008-03-28 at 15:06 +0100, Ingo Molnar wrote:
> * Gerald Schaefer <gerald.schaefer@de.ibm.com> wrote:
> 
> >  include/asm-sh/hugetlb.h      |   28 +++++++++++++++++++++++++
> >  include/asm-sparc64/hugetlb.h |   30 +++++++++++++++++++++++++++
> >  include/asm-x86/hugetlb.h     |   28 +++++++++++++++++++++++++
> 
> these seem largely duplicated - shouldnt there be an 
> asm-generic/hugetlb.h instead, which asm/hugetlb.h could include to get 
> default behavior? It would probably reduce the linecount of your patch 
> as well.

Well the hugetlbfs primitives are architecture specific, aren't they?
Just like the other page table manipulation functions. I find the usual
method to use asm-generic/<xxx> and a lot of defines and #ifdefs to pick
up the correct definition from a generic header file rather hard to
read. In the end each arch that wants to use hugetlbfs has to define
each of the hugetlb primitives. Most of them are rather simple, e.g. the
x86 set_huge_pte_at is just a set_pte_at. One line to define the
primitive. Now we could have an #ifdef block around the default
definition that maps set_huge_pte_at to set_pte_at in asm-generic and an
ARCH_HAS_xx override for architecture that need to do something more
complicated. Somehow that was where we started ..
I think the best way to get rid of the ARCH_HAS_xxx fugliness is to let
each architecture define their primitives, even if it looks like code
duplication.

-- 
blue skies,
  Martin.

"Reality continues to ruin my life." - Calvin.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/